Renewable energy sources include solar energy, wind power, tidal wave energy and the like. A solar power conversion system may include a plurality of solar panels connected in series or in parallel. The output of the solar panels may generate a variable dc voltage depending on a variety of factors such as time of day, location and sun tracking ability. Since the majority of applications are designed to run on 120 volts ac power, solar inverter systems are employed to convert the variable dc voltage of the solar panels to a 120 volts ac power source.
In accordance with the topology difference, solar inverter systems may be divided into four categories, namely micro solar inverter systems, string solar inverter systems, central solar inverter systems and solar inverter systems having power optimizers. A micro solar inverter is an inverter designed to operate with a single solar panel. The micro solar inverter converts the direct current output from the single solar panel into alternating current. A string solar inverter is an inverter designed to operate with a plurality of solar panels connected in series. The string solar inverter converts the direct current output from the plurality of solar panels into alternating current.
In a central solar inverter system, a combiner box is employed to bring the outputs of a plurality of solar panels/strings together and consolidate the incoming power into one main power source. The center solar inverter converts the direct current from the main power source into alternating current. In a solar inverter system having power optimizers, each solar panel is connected to the inverter through a power optimizer. The power optimizer may be implemented as a four-switch buck-boost converter. The four-switch buck-boost converter is used to increase the energy output from the solar panel by tracking the maximum power point of the solar panel.